I've had charges added to my invoice from revising listings as well. Some how it makes ebay think it's a new item or something. Even if all I did was bulk edit all the prices.
Happened to me a few times in the past, it seems to occasionally re-apply the insertion fee, i did not loose any sleep over it, strange how the error which is in ebay's favour has not been fixed but yet if it was an error in our favour it would be sharp fixed.